Process for the recovery and purification of lubricating oils from mineral oils



April 28, 193 F. X.GOVERS 1,802,942

PROCESS FOR THE RECOVERY AND PURIFICATION OF LUBRICATING OILS FROMMINERAL OILS Filed Oct. 18, 1928 4 Sheets-Sheet 1 Z" Z O. 5

-:ZZ J7 15 J3 E: V l H J7 Apt-i] 28, 1931.

Can/617.507?

' F. X. GOVERS- PROCESS FOR THE RECOVERY AND PURIFICATION OF LUBRICATINGOILS FROM MINERAL OILS Filed Oct. 18, 1928 4 sheets-sheet -2 attoz wuagApril 28, 1931. F. x. GOVERS 1,302,942

PROCESS FOR THE RECOVERY AND PURIFICATION OF LUBRICATING OILS FROMMINERAL OILS Filed Oct. 18, 1928 4 Sheets-Sheet 3 V Q'Z F. x. GOVERSPROCESS FOR THE RECOVERY AND PURIFICATION April 28, 1931.

0F LUBRICATING OILS FROM MINERAL OILS v 4 Sheets-Sheet 4 Filed Oct. 18,1928 XUDQQQQQU Patented Apr. 28, 1931 UNITED STATES PATENT OFFICEFRANCIS X. GOVERS, OF LAWRENCEVILLE, ILLINOIS, ASSIGNOR TO INDIANREFINING COMPANY, OF LAWRENCEVILLE, ILLINOIS, A CORPORATION OF MAINEPROCESS FOR THE RECOVERY AND PURIFICATION OF LUIBBICATING OILS FROMMINERAL OILS Application filed October 1a, 1928. Serial No. 313,346.

This invention relates to the improvement in methods of obtaining frommineral oils, fractions suitable for the manufacture of lubricants andto so refining such fractions as to improve the lubricatingcharacteristics of the'resultin oils, and more particularly to suchmetho s as applied to mineral oils containing a substantial amount ofparaffine wax. i

The method not only produces lubricating oils having markedly superiorlubricating values but\in addition thereto gives greatly increasedyields of lubricants and parafline wax from a given amount of crude oil.

Lubricating oils must not only possess the property of forming coherentand adherent films but they must in addition possess body enough for therequired duty. They should flow readily at low temperatures (say F.) andshould retain at high temperatures (say 400 enough body and oiliness (byoiliness is meant the property of being adsorbed by or wetting thesurface of a metal) for the duty required. The components of lubricatingoils should retain, at all times, under conditions of use their mutualsolubility, and the oils shouldnot become cloudy, opaque or show signsof separation at low temperatures. They should not corrode nor tend todissolve the bearing metals under conditions of use, and should containno free carbon.

In the cases of lubricants for internal combustion engines they shouldretain their property of oiliness at high temperatures and underconditions of crank case dilution and should not form an emulsion withwater.

As ordinarily manufactured, lubricants made from naphthene base oilshave the property of retaining at low temperatures the mutual solubilityof component hydrocarbons and the formation of coherent films but arelacking in that they do not have the necessary degree of oiliness underconditions of crank case dilution, or at elevated temperatures.

their mutual solubility, and these oils show signs of cloudiness, due tothe separation of solid hydrocarbons, and lose their oiliness.

As most of the loss of mutual solubility at low temperatures inlubricants made from wax-containing crude oils is due to the separationof para-fline Wax,these lubricants are put through a so-called dewaxingprocess,

which consists of cooling or chilling a fraction containing lubricantsdown to a temperature where the wax separates out and filtering out theseparated wax. Due to difficulties in manufacture this dewaxing isseldom if ever complete.

The usual explanation of the lack of complete dewaxing is that waxexists in two states, an amorphous and a crystalline state, and that theWax in the amorphous state not only does not separate out but preventsthe otherwisecrystallizable wax from separating.

It is common procedure, almost universal, in the manufacture oflubricants from paraffine base crude oils to distill from the crude,

fractions containing the desired lubricants and then to submit thesefractions to a cracking operation, whereby, it is claimed, the

amorphous wax -is converted into the crystallizable body and then tosubmit the .cracked fractions to a dewaxing.process.

' While this cracking operation results in a product that contains lesswax and is, therefore, easier to dewax, the fdewaXing is never completeand the tendency to separation at lowering temperatures remains. Thiscracking operation not only breaks down the so-called amorphous wait butpart of the crystallizable Wax as well, and converts much of tthevaluable lubricating fraction COIIllIl eater as the de ree of erackinincreases.

In an attempt'to retain to a high degree this quality it has beenproposed to limit the cracking effect as far as possible by the use ofdistillation methods calling for lower temperatures under diminishedpressures.

The methods heretofore described calling for the use of diminishedpressuresand a lowered. temperature in distillation do not entirelyprevent the undesirable cracking effect and in the case of crudeoilscontaining considerable quantities of paratfine wax the difficultiesof dewaxing are increased and it has, up to the developement of the newmethod herein described, been impossible to produce a lubricating oil ofthe desired oiliness in which mutual solubility of its component partsat low temperatures is preserved.

Disassociation or decomposition of hydrocarbons under heat is promotedby diminished pressure.

Temperature indications are mean temperature indications only and do notdenote that portions of a mass are not heated higher than such meanindicated temperature.

I have discovered in the manufacture of lubricants that, in order topreserve fully their inherent oiliness and mutual solubility, underconditionsof use, it is not only necessary to remove, in refining, suchportions or fractions as tend to separate under conditions oftemperature or use but it is important to so control the process that noportion of the lubricant has, in the course of manufacture, been heatedabove a definite and fixed point.

I have discovered that, by the use of controlled indirect heating, it ispossible to distill and redistill the fractions of mineral oil suitablefor lubrication under diminished pressure without decomposition ordisassociation, and at the same time preserve the natural oilinessinherent in lubricants made from parafiine base oils.

I have discovered that, by the use of a suitable solvent treatment, itis ossible to separate out from the main b0 y of the lubrifrom thelubricating oils of the cant fraction of the oil such portions as willtend to separate out later under conditions of use and/or loweringtemperature.

I have discovered that, by the use of a mix- .ture of solvents ofdiffering solvent properties, it is possible to get a better se arationesirable portions from those which are undesirable, from a lubricantstandpoint.

I'have discovered that, by the use of suitable solvents and theselection of particular fractions obtained by distillation underdiminished pressure with controlled indirect heating, it is possible toobtain from any given crude oil, lubricating oils characterized by ahigh degreeof oiliness, and maintenance of the mutual solubility of thecomponents even at low temperatures.

By suitable solvent I mean a liquid which at temperatures ofapproximately 100 F. has substantially complete solvent action on amineral oil wax distillate substantially free from constituents having aboiling point equal to or below that of gas oil and at temperatures of 5and below has substantially complete solvent action on the liquidhydrocarbons: therein but substantially no solvent action on the solidhydrocarbons therein and of such a nature that upon cooling a solutionof such mineral oil wax distillate in the solvent liquid to 0 Randremoving the solid hydrocarbons so precipitated and the solvent liquidthe resultingoil has a cold test of substantially 0 F.

In a simple embodiment, my invention con templates'distilling, underconditions of diminished pressure coupled with controlled indirectheating, from crude oils the fractions distilling at a temperaturebetween 400 F. and 620" under alow absolute pressure, advantageouslyabout 5 mm. removingfrom such fraction, by means of a selected andselectivesolvent treatment at a desired tem. perature, and subsequentcooling, such portions as tend to separate out under use of loweringtemperature or tend to lessen the desired oiliness; removing from thelubricating portion the solvent used; treating the portion remainingafter the removal of the solvent to remove sulphur and sulphur bearingbodies; and finally redistilling, under diminished, pressure andcontrolled indirect heat, into fractions differing, in accordance withthe requirements of the trade, as to body and gravity.

The advantages of distilling mineral 011s under diminished pressure orin a so-called vacuum ha-vebeen recognized for many years, and the extraadvantage of a very high degree of vacuum due to the extreme lowering ofthe boiling point of the desired fraction has been-recognized, but theadaptation of very high vacuum operations to commercial products has,been held back because of the peculiar characteristics of the materialunder treatment. Mineral oils having a relatively high viscosity arerather sluggish in heat transfer, and under methods hitherto proposedmuch'of the good effects of high vacuum are destroyed or rendered inpart 1nefiective by reason of the method of heating.

Direct heating of the distilling vessel .by

i which the oil is rapidly'circulated, I use inployed and parts of themass are heated be yond the desired temperature, this tendency tooverheating being accentuated bythe viscosity of the oil and its lowheat conductivity. These difiiculties can be overcome in part by the useof indirect heating, and While this is efl'ective so far as permittingthe control of the heating medium to a greater extent than in the caseof direct fire apparatus and in the prevention of overheating, thecapacity of the apparatus is limited by reason of the sluggishness ofthe oil to absorb and transmit heat in the ordinary types of still. Ihave discovered, however, that if the oil to be distilled is moved athigh velocity, over a heated surface maintained at or about therequisite degree of temperature, the temperature differences between thebody of the oil under treatment and the heating medium, which may be asuitable vapor or liquid, can be kept to a minimum, and that a high rateof heat transfer can be maintained at low temperature differences. Thisresults in a minimum of change in the oil under treatment and the re- Itention of all the desired qualities both in the liquid and solidhydrocarbons.

As means for heating the surfaces over stead of direct heating by flameor products of combustion, a suitable heated fluid advantageouslycirculated to and from a source of heat supply, such as the condensiblevapor of a high boiling compound such as diphenyl, which vapor is ofstable composition at the temperature used, or a molten metal such aslead or a fusible alloy (as described in my Patent No. 1,586,987,patented June 1,1926) The use of mercury vapor under maintained vacuumfor this purpose has been proposed, but is objectionable. The use ofsuperheated steam is not feasible,

. boiling hydrocarbon oils be used because they decompose on continuedheating.

These and other similar methods of heating have become known in the artas indirect heating as distinguished from direct heating by flame orproducts of combustion.

It has been proposed to fractionally separate liquid hydrocarbons bymeans of selective solvents and it has been proposed to use solvents asdiluents in the manipulation of lubricating bearing fractions prior toand during the removal of wax. All the solvents hitherto proposed havenot had suflicient selective solvent action as between the solidhydrocarbons and the liquid hydrocarbons under treatment. Acetone bothin a pure and diluted state. has been proposed as a solvent for theselective separation of differing liquid portions of hydrocarbons. Ithas also been proposed to use various alcohols for such purpose. It hasbeen proposed to use benzol and toluol as diluents. The use of acetoneby itself results in the separation of the liquid nor can high.

bons are entirely separated in such a state as e to permit of easyseparation either by centrifugal force or by means of filtration, andthat after removal of the solvents, the lubricating oils retaintheiroiliness at all temperatures and remain homogeneous at low temperatures.

I have also found that the property of oiliness can be advantageouslyincreased by the removal of undesired fractions of liquid hydrocarbonsby means of a selective solvent.

I will now describe in detail a form of apparatus suitable. for carryingout my process.

Referring to the drawings:

Fig. 1 is an elevation of the apparatus;

Fig. 2 is a sectional detail of the oil heater element;

Fig. 3 is a sectional elevation of a boiler for;1 delivering hot vaporto the oil'heater; an I Fig. 4 is a flow sheet of the entire process.

Referring to Figs. 1, 2 and 3 of the drawings, the apparatus consists ofan evaporator 6, having an outlet 8 connected by flan e 9 to the inlet10 to the condenser 11. on denser 11 is connected to receiver 12 bymeans of a barometric discharge pipe 13. The condenser 11 is furtherprovided with a water inlet 14 and water outlet 15, and is connected toa jet ejector 16 by means of pipe 17. The heating element 5 (shown indetail in Fig. 2) and the evaporator 6 are connected by a circulatingsystem comprising downtake pipe 19, circulating pump 20 and uptake pipe21. The heating element 5 (see Fig. 2) comprises an outer shell 22,provided with headers 23 and 24 into which are expanded tubes 25. Theupperheader 23 is secured to the shell 22 which has, at its lower end anenlarged portion 22 within which is a packing chamber. Extendingupwardly from the header 24 is a cylindrical shell 24, between which and22 packing material, advantageously asbestos fiber, is located, which isheld in place by a gland member 60. This arrangement allows forexpansion of the tubes without undue strain. At itsupper portion theshell 22 is surrounded by a jacket 27. This construction need not befurther specifically described, as it will be apparent from thedrawings. The heating element is advantageously heated by hotvapor'entering through the neck-3O from the pipe 31, pro vided withvalve 56, which is connected to the boiler 32. The heating vapor passesup wardly around through the space between shells 22and the shell 33which surrounds the tubes 25, through which the oil passes, and thevapor then flows downwardly in contact with these tubes. The va or isthereby condensed and collects in the Bottom of the chamber above theheader 24, and flows outwardly through the neck 34 which is connected tothe pipe 35 leading to a pump 36 by which it is returned through pipe 57having check valve 58 to pump 39 and thence through pipe 37 leading intoa chamber 37' at the bottom of the boiler 32.

The boiler 32 is supplied with a high poiling point liquid, such asdiphenyl, delivered by supply pump (not shown) through pipe 38 leadingto a circulating pump 39 from which it is delivered by pipe 37 intochamber 37 and thence into a series of tubes 41 mounted between headers42, 43. The bank of tubes 41 is mounted within a brickwork stack 44which may be heated in any suitable manner, as by hot gases deliveredinto the lower portion of the heating chamber 45 through a connection 46(shown i dotted line) leading to any suitable heat sup ply. The liquidpassing through the pipes is delivered against a spreader 62 into avapor chamber 47 having a safety valve 61, from which chamber the vaporsare delivered through pipe 31 and pressure regulating valves 56, 56' tothe vapor inlet 30 of the heating element 5. A

The unvaporized liquid passes from the chamber 47 through the pipe 48 tothe pump 39 and is circulated through the heated tubes. These pipes 48,31 and 35 are provided with suitable bends-to provide for expansion andcontraction.

From the heating chamber 45 the hot gases maybe delivered into a stack50.-

As a'high boiling liquid, I may advantageously use melted diphenyl,which melts at about 158 F. and boils at about 485 F., and at a pressureof approximately 110 pounds has a temperature of about 750 F.

By means of the system shown, the tubes in the heating element 5 areexternally heated by the hot diphenyl vapor and can therefore be readilymaintained at any desired temperature.

The oil is continuously' forced upwardly by the pump 20 throughtheheated tubes 25 and the mixed liquids and vapors are discharged againstthe spreader 51 in order to permit the separation of the oil vapors fromthe liquid oil which flows downwardly through the pipe 19 to the pump20.

The temperature of the vapor delivered through pipe 31 is controlled byvarying the pressure under which the high-boiling point liquid isvaporized. The temperature'of the tubes through which the oil iscirculated can thus be accurately controlled. The rate at which the oilis heated in its passage through the heated tubes may be controlled byvarying the speed of the circulating pump 20.

There can thus readily be maintained any desired temperature differencebetween the heated. surfaces and the flowing oil in contact therewith,thereby enabling the gradual, uniform heating of the body of oil to thedesired distillation temperature without any danger of overheatingportions thereof, and cuts may be taken off within as narrow ranges oftemperature as considerations may dietate.

All pipes conveying hot liquids or vapors are heavily insulated to avoidloss of heat,

and all pipes containing diphenyl are provided with means forliquefaction or for maintaining the diphenyl in liquid state. The pipes19 and 21 are provided'with slip joints 52 and 53 to provide forexpansion and contraction.

The system is provided at all necessary points with heat and pressureindicating devices.

A specific example ofthe operation of the process and apparatus is asfollows:

1000 bbls. (42 gals. each) of Illinois crude oil are topped in a pipestill in which is distilled ofl ata temperature not in excess of '67 5F. about 28% (of the body of the oil) in the form of a gasoline cut, and17% in the form of a cut suitable for cracking. The remaining 550 bbls.are transferred to a vacuum still as abovedescribed.

- In this still, the oil to be distilled is introduced into the pipe 55and circulated in the manner above described. through the externallyheated tubes 25. The partially vaporized circulating oil from the tubes25 is distributed by the spreader 51 in the form of a curtain, theunvaporized portion going down to the body of the evaporator 6 to becirculated through the circulating system and the vapor portion goingoff through the outlet neck to the condenser ll-where it is condensedand flows through the barometric discharge pipe 13 to the receiver 12.The surface condenser is cooled-by means of water; during this lowpressure, from an initial temperature of approximately 220 F. to a finaltemperature of approximately 400 F. This material can be separated indistillation, into fractions for various uses or may be run oif in onefraction for cracking stock.

There is then distilled oil. under low pressure (advantageously 5 mm.absolute) at an initial temperature of approximately 400 F. and a finaltemperature of approximately 620 F., 250 bbls., which fractionconstitutes a wax distillate. My invention is not limited to the use ofa cut within a wider or a cut or cuts within narrower ranges, may beused as considerations may require.

The residue of 130 bbls. remaining in the vacuum still may be burned orworked up in a special form of vacuum evaporator for still heavier oils.

During the period of distillation, care is taken that the temperature ofthe oil does not exceed 675 F. and that the heating medium used for theindirect heating does not exceed To this wax distillate fraction may beadded its own volume of acetone, and thoroughly mixed at a temperatureof 100 F. It is then cooled to 80 F. and allowed to stand. There is asharp separation into' two layers, and the top layer, containing most ofthe solvent and about 10% of the wax distillate, is drawn off. From thisportion, the acetone is evaporated and the residue treated according tothe useto which it is to be put.

The amount of acetone used depends upon the desired fractionalseparation of the liquid hydrocarbons, and may be more or less than theamount above stated. This fractional separation using acetone may beeffected in one or more operations.

The bottom layer, consisting of about 90% of the original wax distillateand 15% of the acetone used, is mixed with 7000 gals. of benzol and5,425 gals. of acetone heated to 90 F.

and stirred thoroughly.

If it is not desired to make fractional separation of the liquidportions of the wax distillate hydrocarbons, the initial mixing of onevolume of acetone and one volume of wax distillate may be omitted, andthe wax distillate mixed directly with one and onehalf times its volumeof a mixture of equal parts of acetone and benzol, and heated to about90 F.

The mixture of Wax distillate and mixed solvents is then cooled, in aflowing stream and under mild agitation, to a low temperature, such as 5F. or less, and run into grainers where it is stirred until there is acomplete separation between the soluble and insoluble constituents.

This mixture of lubricating oil stock and solvents containing finelydivided separated method for the recovery and refining of lumatter, isthen run through filter presses in which the suspended matter isseparated out. The filter cake is worked up for the recovery andpurification of the parafline wax, and the filtrate is run toevaporators where the solvents are evaporated off. The remainder of acut within this range, as

the filtrate may then be treated with 66 sulfuI'ic acid, and acid andsludge centrifuged ofi, treated at 250 F. with an alkaline solution andthe alkaline solution and separated matter centrifuged off.

The thus treated distillate or lubricating oil stock, about 8,500 gals,is transferred to a vacuum still of the type above described, where itis separated by distillation under low pressure, advantageously of theorder of 5 mm., into the required fractions. This distillation ispreferably conducted in the presence of alkali, as for example causticsoda, either in solution or as a finely divided solid, in theapproximate proportion of aboutl lb. of caustic soda to about 100 gals.of 'oil. For some grades of lubricating oils, the acid and alkalitreatment may be omitted. During such distillation the temperature ofthe heating medium is not allowed to exceed 730 F.

An example of fractional distillation under an absolute pressure ofabout 5 mm. is shown in the following table Gals. Distilled Initial B.P.Final B. P. 582? 0 F o F Sal/001i 1360 380 410 200 1360 410 440 300 440480 450 480 540 850 540 600 1100 Residue The residue can be accumulateduntil there enough for distillation and then be redisis tilled to aheavier'oil than the 1100 viscosity 1n the above example, giving at aninitial boiling point temperature of 600 F. and a bloom, in theirrelation of gravity to absolute viscosity, by their relatively lowcoeflicient of friction under heavy loads, by their freedom from sulphurcompounds and by their absence of corrosive action.

Lubricating oils as found in commerce may have grouped together in agiven oil a few of the desirable properties above enumerated but up tothe discovery of the above described bricating fractions of mineraloils, no lubricating oils have been known to possess, in any given oil,all of the above enumerated desirable qualities and properties.

Examples of the finished lubricating oils produced by this method areshown in the accompanying table:

It will be'obvious from the foregoing that many modifications may bemade in the details of the process without departing from the spirit andscope of my invention. For instance, the chemical treatment may-beapplied to the wax distillate before or after the, dewaxing' treatment.Also certain other fractions of crude oil, such'asjfor example lubricantconcentrates from Pennsylvania type crude oils or chemically treatedlubricant containing concentrates from mixed basecrude oils, areequivalents of the wax distillate given in the foregoing example withrespectto the dewaxing treatment above described.

I claim I a 1. Process ofmanufacturing a low cold test lubricating oilwhich comprises mixing a wax distillate fraction of a mineral oil with asolvent liquid, which at temperatures of approximately100 F. hassubstantially complete solvent action on a mineral oil wax distillatesubstantially free from constituents having a boiling point equal to orbelow that of gas oil and at temperatures of -5 and below hassubstantiall complete solvent action on the liquid hy substantially nosolvent action on the solid hydrocarbons therein and of such a naturethat upon cooling a solution of such mineral oil wax distillate in thesolvent liquid to 0 F. and removing the solid hydrocarbons sorecipitated and the solvent liquid the resulting oil has a cold test ofsubstantially 0 F., cooling the mixture of solvent liquid and waxdistillate fraction to a temperature of 0 F. or below, and removingtherefrom the solid hydrocarbons so precipitated.

2. Process of manufacturing-a low cold test lubricating oil from a waxdistillate fraction of a mineral oil which is substantially free fromconstituents having a boiling point equal to or below that of gas oilwhich comprises mixing the said fraction with a solvent liquid which attemperatures of approximately 100 F. has substantially complete solventaction on said fraction and at temperatures of 5 F and below hassubrocarbons therein but all of the solid hydrocarbons and removing thesolid hydrocarbons so prestantially complete solvent action on theliquid hydrocarbons therein but substantially no solvent action on thesolid hydrocarbons therein and upon removal of solid hydrocarbons andthe solvent the fraction has a cold test substantially the same as thetemperature of the mixture at thetime of the removal of the solidhydrocarbons, cooling the mixture to a temperature of 0 F. or below andremoving therefromthe solid hydrocarbons so precipitated.

3. Process of manufacturin a low cold test lubricating oil from a waxdistillate fraction of a mineral oil which is substantially free fromconstituents having a boiling point equal to or below that of gas oilwhich comprises mixing the said fraction with acetone and benzol in sucha ratio toeach other and to the said fraction that the acetone andbenzol together, at temperatures of approximately 100 F.,. havesubstantially complete solvent action on such fraction, and

at temperatures of 5 F. and below, have v substantially complete solventaction on the liquid hydrocarbons but substantially no solvent action onthe solid hydrocarbons in said fraction and upon removal of solidhydrocarbons and the acetone and benzol such fraction has a cold testsubstantially the same as the temperature of the mixture at the time ofthe removal of the solid hydrocarbons, cooling the mixture to atemperature of. 0 F. or below, and removing therefrom the solidhydrocarbons so precipitated.

4. Process of manufacturing a low cold test lubricating oil from a waxdistillate fraction of a mineral oil which is substantially free fromconstituents having a boiling point equal to or below that of gas oilwhich comprises mixing the said fraction with a solvent liquid which attemperatures of approximately 100 F. has substantially complete solventaction on said fraction and at temperatures of -5 F. and below hassubstantially complete solvent action on the liquid hydrocarbons thereinbut substantially no solvent action on the solid hydrocarbons thereinand upon removal of solid hydrocarbon and the solvent the fraction has acold test substantially the same -as the temperature of the mixing atthe time of the removal of the solid hydrocarbons, cooling the .mixtureto a temperature at which substantially are precipitated cipitated.

In testimony whereof, I afiix my signture.

FRANCIS X. sGOVERS.

